arXiv subjects

Mireille Louys

Publications and source records attributed to Mireille Louys.

At least 19 recordsLinked to original sources

arXiv2025

OntoPortal-Astro, a Semantic Artefact Catalogue for Astronomy

The astronomy communities are widely recognised as mature communities for their open science practices. However, while their data ecosystems are rather advanced and permit efficient data interoperability, there are still gaps between these ecosystems. Semantic artefacts (SAs) -- e.g., ontologies, thesauri, vocabularies or metadata schemas -- are a means to bridge that gap as they allow to semantically described the data and map the underlying concepts. The increasing use of SAs in astronomy presents challenges in description, selection, evaluation, trust, and mappings. The landscape remains fragmented, with SAs scattered across various registries in diverse formats and structures -- not yet fully developed or encoded with rich semantic web standards like OWL or SKOS -- and often with overlapping scopes. Enhancing data semantic interoperability requires common platforms to catalog, align, and facilitate the sharing of FAIR (Findable, Accessible, Interoperable and Reusable) SAs. In the frame of the FAIR-IMPACT project, we prototyped a SA catalogue for astronomy, heliophysics and planetary sciences. This exercise resulted in improved vocabulary and ontology management in the communities, and is now paving the way for better interdisciplinary data discovery and reuse. This article presents current practices in our discipline, reviews candidate SAs for such a catalogue, presents driving use cases and the perspective of a real production service for the astronomy community based on the OntoPortal technology, that will be called OntoPortal-Astro.

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arXiv2022

Annotating TAP responses on-the-fly against an IVOA data model

With the success and widespread of the IVOA Table Access Protocol (1) for discovering and querying tabular data in astronomy, more than one hundred of TAP services exposing altogether 22 thousands of tables are accessible from the IVOA Registries at the time of writing. Currently the TAP protocol presents table data and metadata via a {TAP\_SCHEMA} describing the served tables with their columns and possible joins between them. We explore here how to add an information layer, so that values within table columns can be gathered and used to populate instances of objects defined in a selected IVOA data model like Photometry, Coords, Measure, Transform or the proposed MANGO container model. This information layer is provided through annotation tags which tell how the columns' values can be interpreted as attributes of instances of that model. Then when a TAP query is processed, our server add-on interprets the ADQL query string and produces on-the-fly, when possible, the TAP response as an annotated VOTable document. The FIELD elements in the table response are mapped to corresponding model elements templated for this service. This has been prototyped in Java, using the VOLLT package library and a template annotation document representing elements from the MANGO data model. This has been exercised on examples based on Vizier and Chandra catalogs.

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arXiv2021

TAP and the Data Models

The purpose of the "TAP and the Data Models" Bird of Feathers session was to discuss the relevance of enabling TAP services to deal with IVOA standardized data models and to refine the functionalities required to implement such a capability.

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arXiv2021

Towards a Provenance Management System for Astronomical Observatories

We present here a provenance management system adapted to astronomical projects needs. We collected use cases from various astronomy projects and defined a data model in the ecosystem developed by the IVOA (International Virtual Observatory Alliance). From those use cases, we observed that some projects already have data collections generated and archived, from which the provenance has to be extracted (provenance "on top"), and some projects are building complex pipelines that automatically capture provenance information during the data processing (capture "inside"). Different tools and prototypes have been developed and tested to capture, store, access and visualize the provenance information, which participate to the shaping of a full provenance management system able to handle detailed provenance information.

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arXiv2021

Practical Provenance in Astronomy

Recently the International Virtual Observatory Alliance (IVOA) released a standard to structure provenance metadata, and several implementations are in development in order to capture, store, access and visualize the provenance of astronomy data products. This BoF will be focused on practical needs for provenance in astronomy. A growing number of projects express the requirement to propose FAIR data (Findable, Accessible, Interoperable and Reusable) and thus manage provenance information to ensure the quality, reliability and trustworthiness of this data. The concepts are in place, but now, applied specifications and practical tools are needed to answer concrete use cases. During this session we discussed which strategies are considered by projects (observatories or data providers) to capture provenance in their context and how a end-user might query the provenance information to enhance her/his data selection and retrieval. The objective was to identify the development of tools and formats now needed to make provenance more practical needed to increase provenance take-up in the astronomical domain.

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arXiv2020

Radio Astronomy visibility data discovery and access using IVOA standards

Enhancing interoperable data access to radio data has become a science priority within the International Virtual Observatory Alliance (IVOA). This lead to the foundation of the IVOA Radio astronomy Interest Group. Several radio astronomers and project scientists enrolled in various projects (NRAO, ASKAP, LOFAR, JIVE, ALMA, SKA, INAF, NenuFAR, etc.) have joined. Together they are paving the way to a better integration of their services in the virtual observatory (VO) infrastructure and propose extension of IVOA standards to help achieving this goal. Calibrated radio datasets such as cubes, images, spectra and time series can already be searched and retrieved using the ObsCore/ObsTAP specification defined in the IVOA, or by data product-specific services like SIAv2, SODA, SSA and ConeSearch. However, properties of radio visibility data are not fully implemented in the VO landscape yet. We need specific features to refine data discovery and selection that are adapted to radio astronomers' need. In this context the VO team at the Centre de Données astronomiques de Strasbourg (CDS) proposes to consider the ObsCore/ObsTAP specification and to establish cross-walks between the ObsCore and the existing Measurement Set (MS) metadata profile for data discovery of radio visibility data (VD). In order to account for the difference in granularity between radio VD datasets and science-ready datasets of the VO, the approach splits a MS data file into a list of datasets served by an ObsTAP service, thus enabling coarse grain discovery in the multi-wavelength context. Radio specific metadata such as number of antennae, frequency ranges, $uv$ plane coverage plots, frequency-phase and frequency-amplitude plots, primary and synthesized beams are also provided either by adding column metadata or by using the DataLink technique.

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arXiv2020

Implementation feedback of the IVOA Provenance data model

The IVOA Provenance Data model defines entities, agents and activities as container classes to describe the provenance of datasets, with the executed tasks and responsibilities attached to agents. It also provides a set of classes to describe the activities type and their configuration template, as well as the configuration applied effectively during the execution of a task. Here we highlight lessons learned in the implementation of the CDS ProvHiPS service distributing provenance metadata for the HST HiPS data collections, and for the HST archive original images used to produce the HiPS tiles. ProvHiPS is based on the ProvTAP protocol, the emerging TAP standard for distributing provenance metadata. ProvTAP queries may rapidly become very complex. Various graph representation strategies, including ad hoc solutions, triplestore and SQL CTE have been considered and are discussed shortly.

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arXiv2018

Provenance tools for Astronomy

In the context of astronomy projects, scientists have been confronted with the problem of describing in a standardized way how their data have been produced. As presented in a talk at last year's ADASS, the International Virtual Observatory Alliance (IVOA) is working on the definition of a Provenance Data Model, compatible with the W3C PROV model, which shall describe how provenance metadata can be modeled, stored and exchanged in astronomy. In this poster, we present the current status of our developments of libraries and tools, mainly open source, which implement the IVOA Provenance Data Model in order to produce, serve, load and visualize provenance information. These implementations are also needed to validate and adjust the data model and the standard definitions for accessing provenance. The provenance tools developed and created for the W3C framework are reused and extended when possible to tackle the domain of astronomical data.

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arXiv2018

Provenance as a requirement for large-scale complex astronomical instruments

We developed several pieces of software to enable the tracking of provenance information for the large-scale complex astronomical observatory CTA, the Cherenkov Telescope Array. Such major facilities produce data that will be publicly released to a large community of scientists. There are thus strong requirements to ensure data quality, reliability and trustworthiness. Among those requirements, traceability and reproducibility of the data products have to be included in the development of large projects. Those requirements can be answered by structuring and storing the provenance information for each data product. We followed the Provenance data model, currently discussed at the IVOA, and implemented solutions to collect provenance information during the CTA data processing and the execution of jobs on a work cluster.

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arXiv2016

IVOA Provenance data model: hints from the CTA Provenance prototype

We present the last developments on the IVOA Provenance data model, mainly based on the W3C PROV concept. In the context of the Cherenkov astronomy, the data processing stages imply both assumptions and comparison to dedicated simulations. As a consequence, Provenance information is crucial to the end user in order to interpret the high level data products. The Cherenkov Telescope Array (CTA), currently in preparation, is thus a perfect test case for the development of an IVOA standard on Provenance information. We describe general use-cases for the computational Provenance in the CTA production pipeline and explore the proposed W3C notations like PROV-N formats, as well as Provenance access solutions.

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arXiv2015

IVOA recommendation: Units in the VO

This document describes a recommended syntax for writing the string representation of unit labels ("VOUnits"). In addition, it describes a set of recognised and deprecated units, which is as far as possible consistent with other relevant standards (BIPM, ISO/IEC and the IAU). The intention is that units written to conform to this specification will likely also be parsable by other well-known parsers. To this end, we include machine-readable grammars for other units syntaxes.

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arXiv2014

IVOA Recommendation: Simulation Data Model

In this document and the accompanying documents we describe a data model (Simulation Data Model) describing numerical computer simulations of astrophysical systems. The primary goal of this standard is to support discovery of simulations by describing those aspects of them that scientists might wish to query on, i.e. it is a model for meta-data describing simulations. This document does not propose a protocol for using this model. IVOA protocols are being developed and are supposed to use the model, either in its original form or in a form derived from the model proposed here, but more suited to the particular protocol. The SimDM has been developed in the IVOA Theory Interest Group with assistance of representatives of relevant working groups, in particular DM and Semantics.

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arXiv2014

IVOA Recommendation: IVOA Photometry Data Model

The Photometry Data Model (PhotDM) standard describes photometry filters, photometric systems, magnitude systems, zero points and its interrelation with the other IVOA data models through a simple data model. Particular attention is given necessarily to optical photometry where specifications of magnitude systems and photometric zero points are required to convert photometric measurements into physical flux density units.

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arXiv2011

Lessons learnt in building VO resources: binding together several VO standards into an operational service

The International Virtual Observatory Alliance (IVOA) developed numerous interoperability standards during the last several years. Most of them are quite simple to implement from the technical point of view and even contain "SIMPLE" in the title. Does it mean that it is also simple to build a working VO resource using those standards? Yes and no. "Yes" because the standards are indeed simple, and "no" because usually one needs to implement a lot more than it was thought in the beginning of the project so the time management of the team becomes difficult. In our presentation we will start with a basic case of a simple spectral data collection. Then we will describe several examples of small" technologically advanced VO resources built in CDS and VO-Paris and will show that many standards are hidden from managers' eyes at the initial stage of the project development. The projects will be: (1) the GalMer database providing access to the results of numerical simulations of galaxy interactions; (2) the full spectrum fitting service that allows one to extract internal kinematics and stellar populations from spectra of galaxies available in the VO. We conclude that: (a) with the existing set of IVOA standards one can already build very advanced VO-enabled archives and tools useful for scientists; (b) managers have to be very careful when estimating the project development timelines for VO-enabled resources.

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arXiv2011

Evolution of the IVOA Characterisation Data Model

The Characterisation data model is a standard of the International Virtual Observatory Alliance (IVOA) that describes observational datasets in the multi-dimensional parameter space. Defining three properties: coverage, resolution, and sampling along different physical axes (e.g. spatial, spectral, flux) with variable level of details for the description, this model has been used in several IVOA contexts: Simple Spectral Access Protocol, Spectrum Data Model, ObsTAP (Table Access Protocol for the Core Components of the Observation Data Model. Here we propose a new version which addresses more completely the most detailed level of description (level 4) dealing with variation maps of coverage, resolution, and sampling. It also introduces new specific axes in order to cover various photometric measurements, velocity and polarimetry. Special care is given for composed data sets. These improvements and add-ons follow the evolution of needs expressed to the uptake of VO tools in various observation domains for data discovery but also for data analysis requirements. This is also introduced to tackle use-cases designed to analyse scientifically datasets in the V0 context together with calibration/provenance information.

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arXiv2011

IVOA Recommendation: Observation Data Model Core Components and its Implementation in the Table Access Protocol Version 1.0

This document defines the core components of the Observation data model that are necessary to perform data discovery when querying data centers for observations of interest. It exposes use-cases to be carried out, explains the model and provides guidelines for its implementation as a data access service based on the Table Access Protocol (TAP). It aims at providing a simple model easy to understand and to implement by data providers that wish to publish their data into the Virtual Observatory. This interface integrates data modeling and data access aspects in a single service and is named ObsTAP. It will be referenced as such in the IVOA registries. There will be a separate document to cover the full Observation data model. In this document, the Observation Data Model Core Components (ObsCoreDM) defines the core components of queryable metadata required for global discovery of observational data. It is meant to allow a single query to be posed to TAP services at multiple sites to perform global data discovery without having to understand the details of the services present at each site. It defines a minimal set of basic metadata and thus allows for a reasonable cost of implementation by data providers. The combination of the ObsCoreDM with TAP is referred to as an ObsTAP service. As with most of the VO Data Models, ObsCoreDM makes use of STC, Utypes, Units and UCDs. The ObsCoreDM can be serialized as a VOTable. ObsCoreDM can make reference to more complete data models such as ObsProvDM (the Observation Provenance Data Model, to come), Characterisation DM, Spectrum DM or Simple Spectral Line Data Model (SSLDM).

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arXiv2011

IVOA Recommendation: Data Model for Astronomical DataSet Characterisation

This document defines the high level metadata necessary to describe the physical parameter space of observed or simulated astronomical data sets, such as 2D-images, data cubes, X-ray event lists, IFU data, etc.. The Characterisation data model is an abstraction which can be used to derive a structured description of any relevant data and thus to facilitate its discovery and scientific interpretation. The model aims at facilitating the manipulation of heterogeneous data in any VO framework or portal. A VO Characterisation instance can include descriptions of the data axes, the range of coordinates covered by the data, and details of the data sampling and resolution on each axis. These descriptions should be in terms of physical variables, independent of instrumental signatures as far as possible. Implementations of this model has been described in the IVOA Note available at: http://www.ivoa.net/Documents/latest/ImplementationCharacterisation.html Utypes derived from this version of the UML model are listed and commented in the following IVOA Note: http://www.ivoa.net/Documents/latest/UtypeListCharacterisationDM.html An XML schema has been build up from the UML model and is available at: http://www.ivoa.net/xml/Characterisation/Characterisation-v1.11.xsd

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arXiv2007

ASPID-SR: Prototype of a VO-compliant Science-Ready Data Archive

ASPID stands for the "Archive of Spectral, Photometric, and Interferometric Data". The world largest collection of raw 3D spectroscopic observations of galactic and extragalactic sources is provided. ASPID-SR is a prototype of an archive of heterogeneous science ready data, fed by ASPID, where we try to exploit all the power of the IVOA Characterisation Data Model. Multi-level Characterisation metadata is provided for every dataset. The archive provides powerful metadata query mechanism with access to every data model element, vital for the efficient scientific usage of a complex informational system. We provide a set of access interfaces: SIAP/SSAP, HTTP-based characterisation metadata query, Web-service accepting ADQL/x.

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